A power system is constructed by connecting a power generation facility and a load facility by a power transmission and distribution facility. There are power systems of various scales from a large-scaled system connecting a plurality of large-scaled power plants and many factories, commercial facilities and households to a small-scaled system constructed within a specific facility.
As one of the power generation facilities, there is the one including a power generation system utilizing natural energy such as solar light or wind power. The power generation system utilizing the natural energy is being widely introduced in response to rise of awareness of an energy problem or an environmental problem in recent years. However, the power generation system utilizing the natural energy has a demerit that power cannot be stably supplied since generated power is easily affected by natural factors such as seasons or weather. In order to compensate for the demerit, the power generation facility for which the power generation system and a storage battery system are combined has been taken into consideration.
The storage battery system is used as a means for stabilizing power supplied by the power generation facility to the power system. Formerly, storage of a large amount of power was considered to be difficult, but the storage of the large amount of power is made possible by a storage battery of a large capacity such as a lithium-ion battery or a sodium-sulfur battery being made practical. By connecting the storage battery system including such a storage battery to the power generation system, an operation of charging excess power to the storage battery when supply is excessive compared to demand of the power and compensating for insufficiency of the power by discharge from the storage battery when the supply is insufficient compared to the demand of the power is possible. By combining the storage battery system with the power generation system utilizing the natural energy, the generated power which varies depending on seasons or weather or the like is leveled by charging and discharging of the storage battery, and the power can be stably supplied to the power system.
Note that the applicant recognizes the literature described below as the one related to the present disclosure. PTL 1 discloses a configuration in which a photovoltaic power generation system and a storage battery system are connected and variation of generated power of photovoltaic power generation is suppressed by charging/discharging control of a storage battery.